The invention relates to the field of anatomical dental implant systems. More particularly, the invention relates to the field of impression copings for implant restorations.
Dental restorative systems seek to provide cosmetic and functional replacements for missing teeth. Typically, methods for tooth replacement involve placement of an anchor, called a dental fixture, in the patient""s jaw. The dental fixture is inserted into a hole drilled into the jaw. It provides a receptacle for the replacement tooth. Prior to replacement, however, an impression of the local dentition must be taken. The impression should preserve features of the dentition, including the position and alignment of the site for tooth replacement. An integral feature of this process is the use of an impression coping device, which serves to orient and preserve the impression of the local dentition. This allows a technician to form a replacement tooth that matches the contour and orientation of the natural teeth. The impression coping device typically is placed into the bore of the dental fixture, described above. In some dental restorative systems, a screw or bolt is used to anchor the impression coping device in the dental fixture. Once the impression coping device is screwed into the dental fixture, an impression of the local dentition can be taken.
Proper orientation of a replacement tooth is important both cosmetically and functionally. The impression coping device aids in this process by providing a substrate for an impression of the area in which tooth replacement will occur. The impression is formed around the impression coping device in a patient""s mouth. The impression coping device and the attached impression are then removed from the patient""s mouth, and are used as a basis for construction and orientation of a replacement tooth by a dental technician.
Typically, a screw assembly is used to secure an impression coping device to an implanted dental fixture. A dental fixture, therefore, generally consists of a central bore with screw threads for receiving a screw. The exposed surface (i.e., the surface of the fixture protruding from bone) of an implanted dental fixture typically consists of a hexagonal or round interface for defining the orientation of attachment of a tooth analog. An impression coping device is attached to the dental fixture by a screw that threads through the coping and into a central bore of the fixture. The screw mates with threads in the fixture in order to secure the impression coping. An impression of the dentition surrounding the tooth to be replaced is then taken. The impression then is removed from the mouth and used to fabricate a tooth analog, as indicated above.
In the art, in order to obtain a proper fit of the tooth analog, it is desirable to maintain rotational alignment between the implanted fixture and the patient""s natural dentition. This requires that the impression coping device engage the implanted fixture in a non-rotational manner. Some screw mechanisms used to secure impression copings tend to interfere with the rotational alignment of the impression.
Difficulties in handling and properly installing screws or bolts to secure coping devices have lead to improvements, such as an interlocking coping device comprising a screw that is non-removably inserted through the central bore, thus allowing insertion of the coping device and the screw in one step.
Some of the major manufacturers in the dental restorative industry produce dental fixtures. In some instances, these dental fixtures have a male hexagonal head on the end of the dental fixture that protrudes from the patient""s jaw. Manufacturers typically will produce a variety of dental fixtures having differentially-sized male hexagonal heads (often two or three sizes of male hexagonal head). The male hexagonal head of the dental fixtures mates with a female hexagonal mating surface on an impression coping device. A dental professional chooses a dental fixture appropriate for a particular application and uses an impression coping having an appropriately-sized, female hexagonal mating surface to mate with the dental fixture. Moreover, depending on the manufacturer, different dental fixtures may have a unique threaded bore that accepts a screw that interacts with a dental impression coping.
The invention provides platforms for holding and selecting impression copings during various dental procedures. Accordingly, the invention allows rapid and accurate selection of appropriate impression copings during a dental procedure, thus reducing trial and error selection of impression copings and the necessity to preselect impression copings prior to taking an impression. The platform also allows a dental professional to conveniently select and sterilize an amount of impression copings prior to undertaking the procedure. Often, prior to undertaking a dental procedure, the dental professional does not know which size dental fixture(s) will be used. As such, the dental professional must ensure that a sufficient number of impression copings are prepared prior to undertaking the procedure, and often must guess at the correct sizes that will be necessary. The invention provides platforms that hold a selection of impression copings that are complementary to available dental fixtures. A single platform according to the invention may be used for a single procedure, thus reducing the necessity for multiple sterilizations and preselection of multiple impression coping types. Accordingly, in some embodiments of the invention, the dental professional need only choose and sterilize one platform for each dental fixture that will be used during the procedure (or that is already implanted in the patient""s jaw if the dental fixture implantation and the impression-taking are not occurring during the same procedure). This convenience is especially apparent when more than one dental fixture is involved.
The present invention also provides fasteners, such as, but without limitation, screws, for use with impression copings. To the extent that an impression coping is held in place or is supplementally seated with a fasteners, fasteners, such as, but without limitation, screws, according to the invention have at least two separate threaded areas to accommodate variously-sized dental fixtures. As such, the dental professional can quickly mate and secure an impression coping to various dental fixtures having differently sized threaded bores with a screw that engages with the threaded bores, without having to choose a correctly sized screw. Moreover, only a single screw need be supplied, rather than multiple screws, to provide a fastener for various dental fixture sizes.
The invention is not limited to dental fixtures having a male hexagonal head, but this example provides a useful paradigm. For example, some other dental fixture manufacturers in the industry produce fixtures that utilize other types of interfaces between the fixture and the impression coping. For example, the fixture can have a female hexagonal mating surface and the impression coping can have a male hexagonal head, or, for example, the dental fixture can contain teeth that mesh with a complementary structure on the impression coping. These dental fixtures utilizing alternative mating options also can be produced in various sizes such that variously-sized impression copings and/or fasteners are necessary. Thus, in any situation in which variously-sized dental fixtures are sold, variously-sized impression coping devices are necessary for attaching to the variously-sized fixtures. Furthermore, variously-sized threaded screws are necessary to attach to the variously-sized dental fixtures when such fasteners are necessary.
In a preferred embodiment of the invention, a fastener for use with an impression coping includes a first threaded portion and a second threaded portion. The first threaded portion is along an axis and has a first major diameter, and the second threaded portion is along the axis and has a second, different major diameter. The first threaded portion and the second threaded portion are separated by an unthreaded portion.
In some embodiments, a fastener of the invention includes a third threaded portion that is along the axis and is separated from the second threaded portion by a second unthreaded portion. Also in a preferred embodiment, a fastener of the invention includes a first major diameter that is smaller than a second major diameter. In certain embodiments, the first threaded portion is located closer to a distal end of the fastener than the second threaded portion. A preferred fastener according to the invention includes a bulge that is concentric with the axis of the fastener at a location that is closer to a proximal end of the fastener than is the second threaded portion. A fastener of the invention also can include a shoulder that is concentric with the fastener axis at a location that is closer to the distal end of the fastener than is the bulge. In some embodiments, the invention provides a fastener including a first threaded portion and a second threaded portion, at least one of which has a major diameter of about 1 millimeter to about 3 millimeters. Also, in some embodiments, the first threaded portion has a major diameter of between about 1 millimeter to about 2 millimeters, and the second threaded portion has a different major diameter of between about 1.5 millimeter to about 3 millimeters. In embodiments with a third threaded portion, the third threaded portion may have a major diameter of about 1 millimeter to about 3 millimeters. Fasteners according to the invention are not limited to these dimensions. In some preferred embodiments, at least one of the threaded portions can engage with a dental fixture, and/or an impression coping can be seated on the dental fixture.
Another aspect of the invention provides methods for seating an impression coping. Methods of the invention include the steps of providing a fastener, inserting the fastener through an impression coping; and, securing the fastener to a dental fixture. Fasteners for use in methods of the invention preferably are selected from those described above as well as below.
In another aspect of the invention, a dental impression kit includes an impression coping and a fastener for inserting through the impression coping to seat the impression coping on a dental fixture. In certain embodiments, the fastener includes a first threaded portion and a second threaded portion. The first threaded portion is along an axis and has a first major diameter. The second threaded portion is along the same axis and has a second, different major diameter. The first threaded portion and the second threaded portion are separated by an unthreaded portion. In some embodiments, the impression coping is of a length that exposes a selected portion of the fastener when the fastener is inserted though the impression coping. In some preferred embodiments, the fastener can include a bulge that is concentric with the axis and has an outer diameter that is larger than an inner diameter of a lip located within the impression coping. The fastener and impression coping also can interact with a radial interference interaction.
In another aspect of the invention, a dental impression tool support kit includes a platform and at least one impression coping attached to the platform at a frangible connection. In certain embodiments, the kit includes a reinforcing member attached to the platform at a frangible connection. In some embodiments, from about one to about seven impression copings are attached to a single platform. Any of the impression copings may include a head for releasable mating with a dental fixture, and the heads may be differently-sized for mating with differently-sized dental fixtures. At least one of the impression copings may include a female, hexagonal structure, and a platform may include a male, hexagonal structure for mating with the impression coping having the female, hexagonal structure.
In another aspect of the invention, a dental impression kit includes a platform, at least one impression coping attached to the platform, and a fastener for inserting through the impression coping. In certain embodiments, the kit can include a reinforcing member attached to the platform and/or can include from about one to about seven impression copings attached to the platform. In some embodiments, the fastener can include a first threaded portion and a second threaded portion. The first threaded portion is along an axis and has a first major diameter. The second threaded portion is along the axis and has a second, different major diameter. The first threaded portion and the second threaded portion are separated by an unthreaded portion.
In another aspect of the invention, a member for supporting a dental impression includes a first arcuate portion having a first profile, a second arcuate portion disposed adjacent the first arcuate portion and having a second, different profile, and a third portion protruding from the member at an intersection of the first and second portions. A section of the member can be selectively detachable at a frangible connection. In another aspect of the invention, a method for reinforcing a dental impression includes providing a member as described immediately above, or below, and inserting the member into an impression material.